Thermal processing torches, such as plasma arc torches, are widely used in the heating, cutting, gouging and marking of materials. A plasma arc torch generally includes an electrode, a nozzle having a central exit orifice mounted within a torch body, electrical connections, passages for cooling, and passages for arc control fluids (e.g., plasma gas). Optionally, a swirl ring is employed to control fluid flow patterns in the plasma chamber formed between the electrode and the nozzle. In some torches, a retaining cap can be used to maintain the nozzle and/or swirl ring in the torch body. In operation, a plasma arc torch produces a plasma arc, which is a constricted jet of an ionized gas with high temperature and sufficient momentum to assist with removal of molten metal.
A plasma arc torch can be powered by a removable energy storage device, such as a battery pack, to enable cordless torch operation. For example, U.S. Pat. No. 7,183,517, hereinafter referred to as the '517 patent, discloses a portable welding-type apparatus with a removable energy storage device. An external power source provides power to a charger, which may be used to charge the energy storage device. The voltage output of the energy storage device is provided to a boost circuit configured to boost the voltage output of the energy storage device to a second voltage to power the welding-type apparatus according to a selected welding-type process. In the '517 patent, because the energy storage device is located between the external power source and the boost circuit, a different charger for charging the energy storage device is needed each time the external power source provides a different input voltage. Alternatively, restrictions can be placed on the amount of input voltage supplied by the external power source of the '517 patent, but at the expense of limiting the usage of the battery-powered apparatus. Moreover, in the '571 patent, extra external hardware is needed to charge the energy storage device. Because this hardware is external to the plasma power supply, it is less integrated in comparison to a system that can use the existing control hardware and/or software to regulate the charge of the energy storage device. In addition, the power generated by the energy storage device of the '571 patent needs to pass through additional circuit components (e.g., a boost circuit) prior to reaching the torch, which creates inefficiency and energy loss.